With the progress of post-genome studies, it has become necessary to analyze the protein structure urgently. In order to do that, however, it is necessary to crystallize protein. Furthermore, organic crystals are considered as promising next-generation device materials. Accordingly, there are great needs for the technique of producing high-quality organic crystals. Generally, in order to deposit crystals from a solution, it is necessary to increase the degree of supersaturation through solvent evaporation, a temperature change, etc. However, a substance with a high molecular weight such as an organic substance or protein is not crystallized unless the supersaturation degree is extremely high. Once crystallization takes place in such a solution whose supersaturation degree is extremely high, the crystal grows rapidly. Hence, there is a possibility that the crystal to be obtained thereby may have a problem in its quality. Furthermore, such a high-molecular-weight substance generally is difficult to crystallize, which results in low productivity. Usually, crystallization conditions are determined as a result of trial and error through actual attempts of crystallization. This, however, is too complicated to be practical in the case of substances such as protein, an organic substance, etc. that must be crystallized. There is an attempt to produce an organic crystal using a nanosecond Nd:YAG laser (Physical Review Letters 77 (1996) p3475; JP2002-068899). In this method, however, crystallization is not achieved satisfactorily and it is particularly difficult to crystallize protein.